Multi-point rotary switch with improved detent arrangement



Sept. 6, 1966 E MGFADDEN 3,271,534

MULTI-IOINT ROTARY SWITCH WITH IMPROVED DETENT ARRANGEMENT Filed March25, 1965 5 Sheets-$heet l Sept. 6, 1966 MOFADDEN MULTI-POINT ROTARYSWITCH WITH IMPROVED DETENT ARRANGEMENT Filed March 23. 1965 5Sheets-Sheet 2 Sept. 5, 1966 MCFADDEN 3,271,534

MULTI-POINT ROTARY SWITCH WITH IMPROVED DETENT ARRANGEMENT Filed March23, 1965 5 Sheets-Sheet 5 United States Patent M and Northrup Company,Philadelphia, Pa., a corporation of Pennsylvania Filed Mar. 23, 1965,Ser. No. 442,072 4 Claims. (Cl. 20011) This invention relates tomulti-point rotary switches and particularly those of type having adetent arrangement for releasably restraining the contact-operatingshaft in its various point-positons.

In accordance with one aspect of the present invention, the detentarrangement of the switch assembly comprises a stationary annulus havinga notched inner periphery engaged by at least one of a pair of rollersdisposed on opposite sides of the switch shaft and whose axles areslidably received by radial slots of a carriage mounted on the shaft.The detenting force is supplied by a free leaf spring whose oppositeends respectively engage the axles of the rollers. Such spring androller arrangement imposes no frictional load on the shaft but doesrequire application of a predetermined minimum torque for movement ofthe shaft in either direction from one detent position to the next.

More particularly, the aforesaid stationaryannulus is clamped betweentwo housing members of the switch assembly to extend between the sidemembers of the roller carriage. In one form of the invention, the innerperiphery of such housing members provides a smooth track for one of.said pair of rollers whereas in another modification both rollers ridethe notched periphery of the annulus to increase the turning torquerequired for a given roller-biasing spring.

Also in accordance with the invention, the one or more movable contactassemblies of the switch each includes a hub slidably but non-rotatablymounted on the shaft, with the contact pressure balanced to avoidbinding of the hub on the shaft. More particularly, the hub bores arehexagonal or other multi-sided shape to fit a similarly shaped shaft:Accordingly, the contact assemblies of a multi-pole switch may bemounted on the shaft in any of various fixed angular relations to theother and may be paired in back-to-back relationship to equalize thepressure applied by them to their associated fixed contacts.

Further in accordance with the invention, an array of fixed contactscorresponding with each movable contact assembly is integrally molded ina housing element keyed to an adjacent housing element to insure propercorrespondence between the contact positions and the notches of thedetent annulus which is also keyed to one of the housing elements.

Further in accordance with the invention, the switch assembly includesone or more backing spiders each engaged by one of said adjacent housingelements to resist bending of a fixed contact ring by the associatedmovable contact brush.

Also in accordance with the invention, the switch assembly includes astop arm slidably but non-rotatably received by the hexagonal or othermulti-sided shaft and engagable by at least one stop pin as insertedthrough a selected one of a series of angularly spaced holes extendingthrough a front housing member of the switch assembly. The stop pin orpins are retained by a washer arrangement removable for resetting of thestop pin positions without disassembly of the switch.

More particularly, the stop arm and roller carriage are held in fixedaxial position on the shaft by a pair of split washers; one of saidwashers cooperates with a third split washer and a shaft bearing sleevein said 3,271,534- Patented Sept. 6, 1966 front housing member toprevent axial movement of the shaft, the stop arm and the rollercarriage, all with respect to the stop pins and detent annulus asmounted on the housing members.

The invention further resides in a multi-point rotary switch havingnovel and useful features of construction, combination and arrangementhereinafter described and claimed.

For a more detailed understanding of the invention, reference is made tothe following description of embodiments thereof and to the accompanyingdrawings in which:

FIG. 1 is a perspective view of an assembled switch unit;

FIG. 2 is a sectional view, on enlarged scale, of the switch unit ofFIG. 1;

FIG. 3 is an exploded view showing in perspective the various individualcomponents of the switch unit of FIGS. 1 and 2;

FIG. 4 shows, in perspective, the components of a modification of asub-assembly of the detent roller and spring arrangement of FIGS. 2 and3; and

FIG. 5 is a sectional view similar to FIG. 2 but including a secondmovable contact assembly and its associated fixed-contact housingcomponent.

Referring to FIGS. 1 to 3, the switch unit 10 comprises a front housing11, a rear housing 12 and a fixed-contact housing ring 13, and a spacerhousing ring 14. The operating shaft 15 for the movable contactstructure of the switch is supported at one end by a bearing sleeve 16held in the front housing 11 by nut 17 and at the other end by a blindbearing sleeve 18 formed in the rear housing 12. The housings 11, 12,one or more contact-housing rings 13, spacer ring 14 and detent annulus23 are releasably clamped in assembled relation by the bolts 19 whichpass through the holes 20A-20N and slots 25, 25 of the stack of housingmembers for threaded engagement by nuts 21.

The adjacent faces of housing members 11 and 14 are respectivelyprovided with grooves 22A, 22B to receive the detent annulus 23 whoseinner circumference has a series of notches or teeth 24 in numbercorresponding with the number of active switch positions. The particularannulus shown in FIG. 3 is for an ll-position switch; for a 12-positionswitch, an additional notch would be cut at location 24A. In all casesfrom a 2-position switch to a l2-position switch, the same notch sizemay be used. The pair of slots 25 in the edge of annulus 23 is to passthe clamping bolts 19, 19; the unsymmetricallylocated slot 26 is forengagement by stud 27 of housing member 14, so to orient the detentannulus. The desired orientation of the detent teeth or notches withrespect to fixed electrical contacts of the contact ring 13 is insuredby providing the adjoining faces of ring 13 and spacer ring 14 withcomplementary pairs of tongues and grooves. Specifically, the tongue 28of the housing member 14 is received by the 180 recess 29 of contactring 13 and the 180 tongue 30 of ring 13 is received by the 180 recess31 of housing member 14. For ganging or stacking of several contactrings 13 in a multi-pole switch, the opposite face of ring 13 is alsoprovided with a groove 33 and a tongue 34 each having an angular extentof 180. Accordingly, to permit the end housing 12 to be assembled, itsinner face is provided with a tongue and recess each 180 in angularextent to mate with the groove 34 and recess 33 of the rearmost contactring 13.

As shown in FIGS. 2 and 3, the group of fixed contacts 36 projectsthrough the housing ring 13 in an array of angularly spaced contactsconcentric with the shaft 15. Preferably, such contact arrangement ismade from a single silver punching whose ears 36, 37 are molded in 123by the bridging structure 60 or equivalent.

the plastic ring 13. After molding, the silver web is punched out toform the contact configuration desired. The particular contact wafershown in FIG. 3 is for an ll-position shorting type switch with a commoncontact ring 37. The outer ends of contacts 36 extend exteriorly of thehousing ring 13 for attachment of wires to the controlled circuits. Theinner ends of contacts 36 extend freely inwardly of the ring forsequential engagement by the long brush ends 46 of the bridging contacts45 of the movable contact assembly 52. The common contact ring 37 issupported in the plane of fixed contacts 36 by its tail extension 37A-which extends through the housing ring 13 for external connection to acircuit conductor. The contact ring 37 is continuously engaged by theshorter brush ends 47 of the two outer contact springs-of the brushassembly 45. To maintain firm contact pressure, flexing of the contactring 37 by brush pressure is precluded by its'backing engagement withthe plastic spider 38 (FIG. 2). The arms 39 of spider 38 are engaged bythe backing flange 40 of the spacer housing ring 14. The notch 41 (FIG.3) in the hub 'of spider 38 accommodates the tail extension 37a ofcontact ring 37.

As best shown in FIG. 2, the bridging contacts 45 encircle the hubelement 50 and at two points spaced somewhat less than 90" on each sideof their selector end 46 are held as by rivets 48 to the arms 49extending in opposite directions outwardly from hub 50. The bore of'hub50 of'the movable contact assembly 52 is hexagonal or otherstraight-sided configuration, slidably to .fit the correspondinglyshaped section 51 of the operating shaft 15 of the switch. In FIG. 2,the rear face of hub 50 of contact assembly 52 is pressed by the contactsprings against the rear bearing 18 in housing member -12. The hub 50 isfree to slide with respect to shaft 15 to maintain a contact pressurewhich is independent of any force applied to shaft 15.

It is to be noted that the common brush 47 and the selector brush 46both tend to push the contact assembly 52 in the same direction axiallyof the shaft, and their 180 orientation further precludes any tendencyfor the assembly 52 to lock or bind on the shaft. In a 2-pole assembly,such as shown in FIG. 5, the two assemblies 52 may be placed back-toback so that the contact forces oppose one another so to minimize torque.losses due to friction of the contact assemblies against any stationaryparts of the switch. Also, in a multi-pole switch, one movable brushassembly can be oriented in any of its six positions on the hexagonalshaft 15'so that its selector brush 46 may be set to lead or lag theradial slots 58, 59. The side members 57 of the carriage are held infixed spaced relation to span the detent ring One pair of slots, forexample, 58, 58, receives the opposite ends of the axle of the detentroller 61A, and in the arrangement shown in FIGS. 2 and 3, the otherpair of slots,

for example, 59, 59, receives the opposite ends of the axle of the dualidler roller 62. The movable detent sub-assembly is made by insertingthe rollers 61, 62 through the central hexagonal opening in carriage 56,moving them radially in their respective pairs of slots, and thensnapping the C spring 63A to engage the roller axles. With suchsub-assembly incorporated in the switch unit, the detent ring 23 isclamped in fixed position between the housing members 11, 14. The roller61A is biased by spring 63A to engage the notched inner periphery ofring 23 and the dual idler roller 62 is biased against the smooth innerperipheries of the housings 11, 14. With shaft 15 in any of its detentpositions, the

roller 61A is seated in one of the notches of detent ring 23 and attemptto turn shaft 15 causes the roller 61A to ride up one side of the notch,its axle moving in the slots 58, 53 against the compression force ofspring 63. A substantial minimum torque is required to move roller 61Ain either direction from one detent position to the next. It is to benoted that the single leaf spring 63A which supplies the detenting forcereceives its reaction force from the switch housing without loading theswitch shaft in any way. Use of detent rollers affords relatively largecontacts area with the fixed detent plate, so keeping stresses to aminimum; the construction shown also allows the biasing spring to bearon and provide a bearing for a diameter much smaller than the diameterof the rolls so assuring a rolling rather than a sliding action in onedetent position to the next. With the construction shown in FIG. 2, theminimum torque requirements may, of course, be increased by using aheavier C-spring.

Alternatively, to increase the torque requirements, the dual idler roll62 may be replaced by a second detent roll 61b (FIG. 4), in which casespring 63a is replaced by spring 63b, both of whose ends are forked tostraddle the detent rolls 61A, 61B for engagement with the respectiveaxles thereof. In this modification, the rollers 61A, 61B areconcurrently received by diametrically opposite notches of thestationary detent plate 23. The forward end of the hexagonal shaftsection 55 also receives the stop member 65 having a mating hexagonalbore and an offset leg 66. The split spring washers 68, 69 as sprunginto the grooves at opposite ends of shaft section 55 hold both the stopmember 65 and the detent carriage 56 in fixed position axially of shaft15. A third split spring washer 67 is received by a groove in shaft 15to bear against the outer end of bearing sleeve 16; thus, with.was-her'69 bearing against the inner end of sleeve 16,

the shaft 15 is prevented from having any appreciable axial movement orend-play with respect to the housing members 11 et seq.

The range of angular movement of shaft 15 is determined by one or morestop pins 70 which can be inserted through any one of the twelve holes71 in the front face of housing member 11. For the ll-position switchshown, one stop pin may be used to define both limits of rotation ofshaft 15. Two stop pins are used for a lesser number of active switchpositions. The stop pin or pins 70 are held in selected position by ringwasher 72 which overlies the enlarged pin-head structure and is engagedby the split washer 73 as sprung into groove 74 of sleeve 16. Thecircular recess 75 in the front face of housing 11 may be of depth suchthat the retaining washer 73 is substantially flush with the front faceof the housing 11. The

position of stop pin 70 can be adjusted, without disassembling theswitch unit, by removing washers 73, 72 and inserting pin 70 in its newposition. The washers 72, 73 are then replaced to retain pin 70 in itsnew adjusted position. The central hexagonal recess 76 of housing 11mates with the similarly shaped boss 77 of the shaft bearing sleeve 16,so that the sleeve is prevented from turning without need for excessivetightening of nut 17. For

'manual operation of shaft 15, there may be provided a knob 80 having aset screw 81 for engaging a flat 82 i of shaft 15.

It is to be understood the invention is not limited to the 'specificconstruction shown, but comprehends modificaa pair of carriage membersmounted on said shaft for rotation therewith, each of said membershaving radial slots on opposite sides of the shaft and paired withparallel radial slots of the other carriage memher,

a stationary internally-notched annulus mounted on said housingconcentric to said shaft and in a plane which extends between saidcarriage members,

a pair of rollers having axles respectively received by a correspondingone of the pairs of said radial slots, and

a leaf spring structure freely spanning said shaft and having itsopposite ends respectively engaging said axles to bias said rollers inopposite directions away from said shaft, each of said spring end-sbeing shaped to provide a bearing for the axle of the associated rollerand at least one of said rollers cooperating with said internallynotched annulus and said leaf spring structure to apply detent pressurein direction radially of said shaft.

2. A multi-position rotary switch as in claim 1 in which each of bothends of said leaf spring structure is forkshaped to embrace theassociated roller and to provide bearings for axle extensions atopposite ends of said roller, both of said rollers as biased by saidleaf spring structure engaging the notched inner periphery of saidannulus.

3. A multi-position rotary switch as in claim 1 in which one end of saidleaf spring structure is fork-shaped to embrace a first of said rollersand to provide axle bearings at opposite ends of said roller; the otherend of said leaf spring structure is shaped to extend between the spacedroller elements of the second roller and to provide a bearing for theaxle extending between said spaced roller elements; said leaf springstructure biasing said first roller against the notched inner peripheryof said annulus and the roller elements of said second roller againstthe smooth inner periphery of said housing.

6 4. A multi-position rotary switch as in claim 1 which includes atleast one pair of said movable contact assemblies,

each of said assemblies comprising hub structure slidably butnon-rotatably mounted on said shaft and having a dual arm contact brushstraddling said shaft in avoidance of binding of the hub structure onsaid shaft, and

two housings for each pair of said movable contact assemblies, each ofsaid housings having angularlyspaced fixed contacts for selectiveengagement by one arm of the dual arm contact brush of the associatedone of said assemblies and having a contact ring for continuousengagement by the other arm of said assembly,

the movable contact assemblies of each pair thereof being orientedback-to-back on said shaft for equalization of the contact pressuresrespectively produced by them axially of said shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,264,045 11/1941 Maier 200-11 2,831,368 4/1958 Bauer 74527 3,144,711 8/ 1964Stevens.

3,188,404 6/1965 Fichter 200-14 3,206,564 9/1965 Hauser 20011 ReferencesCited by the Applicant UNITED STATES PATENTS 1,616,277 2/1927 Osborn.2,883,482 4/1959 Huetten et al. 2,980,770 4/1961 Nabstedt. 3,013,23112/1961 Meadows et al.

ROBERT K. SCHAEFER, Primary Examiner. KATHLEEN H. CLAFFY, Examiner.

I. R. SCOTT, Assistant Examiner.

1. A MULTI-POSITION ROTARY SWITCH COMPRISING A HOUSING FOR AT LEAST ONEGROUP OF ANGULARLY SPACED FIXED CONTACTS, A ROTATABLE SHAFT CARRYING ATLEAST ONE MOVABLE CONTACT ASSEMBLY, EACH OF SAID CONTACT ASSEMBLIESCOMPRISING RESILIENT BRUSH STRUCTURE EXTENDING RADIALLY FROM SAID SHAFTFOR SELECTIVELY ENGAGING A CORRESPONDING GROUP OF SAID FIXED CONTACTSAND APPLYING CONTACT PRESSURE IN DIRECTION AXIALLY OF SAID SHAFT, A PAIROF CARRIAGE MEMBERS MOUNTED ON SAID SHAFT FOR ROTATION THEREWITH, EACHOF SAID MEMBERS HAVING RADIAL SLOTS ON OPPOSITE SIDES OF THE SHAFT ANDPAIRED WITH PARALLEL RADIAL SLOTS OF THE OTHER CARRIAGE MEMBER, ASTATIONARY INTERNALLY-NOTCHED ANNULUS MOUNTED ON SAID HOUSING CONCENTRICTO SAID SHAFT AND IN A PLANE WHICH EXTENDS BETWEEN SAID CARRIAGEMEMBERS, A PAIR OF ROLLERS HAVING AXLES RESPECTIVELY RECEIVED BY ACORRESPONDING ONE OF THE PAIRS OF SAID RADIAL SLOTS, AND A LEAF SPRINGSTRUCTURE FREELY SPANNING SAID SHAFT AND HAVING ITS OPPOSITE ENDSRESPECTIVELY ENGAGING SAID AXLES TO BIAS SAID ROLLERS IN OPPOSITEDIRECTIONS AWAY FROM SAID SHAFT, EACH OF SAID SPRING ENDS BEING SHAPEDTO PROVIDE A BEARING FOR THE AXLE OF THE ASSOCIATED ROLLER AND AT LEASTONE OF SAID ROLLERS COOPERATING WITH SAID INTERNALLY NOTCHED ANNULUS ANDSAID LEAF SPRING STRUCTURE TO APPLY DETENT PRESSURE IN DIRECTIONRADIALLY OF SAID SHAFT.